1. Field of the Invention
The present invention relates to methods and compressible sealant compositions for sealing expandable pipe in well bores.
2. Description of the Prior Art
A new well completion practice has been developed whereby casings and liners are expanded diametrically after they are placed in well bores. Prior to the expansion, a sealing composition is placed in the annulus between the walls of the well bore and the unexpanded casing or liner. A problem which can be encountered involves the use of hydraulic cement compositions as the sealing composition. Hydraulic cement compositions are non-compressible and tend to resists the expansion of the casing or liner making the expansion more difficult. In addition, if the cement composition gels or sets prior to when the expansion is accomplished, the cement composition is crushed in the annular space between the walls of the well bore and the expandable casing or liner whereby it does not function to seal the expanded casing or liner in the well bore.
Thus, there are needs for improved sealant compositions for sealing expandable casings or liners in well bores which are compressible and maintain the properties required to provide a seal between the walls of the well bore and the expanded casings or liners.